<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Fundamentals</title>
    <link href="resources/threejs-tutorials.css" rel="stylesheet" />
    <style>
    html, body {
      margin: 0;
      height: 100%;
    }
    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

<script type="module">
import * as THREE from 'three';
import {OrbitControls} from 'three/addons/controls/OrbitControls.js';
import {GLTFLoader} from 'three/addons/loaders/GLTFLoader.js';

function main() {
  const canvas = document.querySelector('#c');
  const renderer = new THREE.WebGLRenderer({canvas});
  const scene = new THREE.Scene();

  const aspect = 2;  // the canvas default
  const fov = 35;
  const near = 0.1;
  const far = 5000;
  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
  camera.position.x = -0.;
  camera.position.y = 350;
  camera.position.z = 40.;

  const useFog = true;
  const useOrbitCamera = false;
  const showHelpers = false;
  const camSpeed = 0.2;

  if (useOrbitCamera) {
    const controls = new OrbitControls(camera, canvas);
    controls.target.set(0, 100.01, 0.2);
    controls.update();
  }

  renderer.outputEncoding = THREE.sRGBEncoding;
  renderer.shadowMap.enabled = true;

  const hemiLight = new THREE.HemisphereLight(0xffffff, 0xffffff, 0.6);
  hemiLight.color.setHSL(0.6, 1, 0.6);
  hemiLight.groundColor.setHSL(0.095, 1, 0.75);
  hemiLight.position.set(0, 50, 0);
  scene.add(hemiLight);

  if (showHelpers) {
    const hemiLightHelper = new THREE.HemisphereLightHelper(hemiLight, 10);
    scene.add(hemiLightHelper);
  }

  const dirLight = new THREE.DirectionalLight(0xffffff, 1);
  dirLight.color.setHSL(0.1, 1, 0.95);
  dirLight.position.set(-300, 220, 245);
  scene.add(dirLight);
  dirLight.castShadow = true;
  dirLight.shadow.mapSize.width = 2048;
  dirLight.shadow.mapSize.height = 2048;
  const d = 350;
  dirLight.shadow.camera.left = -d;
  dirLight.shadow.camera.right = d;
  dirLight.shadow.camera.top = d;
  dirLight.shadow.camera.bottom = -d;
  dirLight.shadow.camera.near = 100;
  dirLight.shadow.camera.far = 950;
  dirLight.shadow.bias = -0.005;

  if (showHelpers) {
    const dirLightHeper = new THREE.DirectionalLightHelper(dirLight, 10);
    scene.add(dirLightHeper);
  }

  const loader = new GLTFLoader();
  const camRadius = 600;
  const camHeight = 160;
  const camTarget = [0, 30, 0];
  const fogNear = 1350;
  const fogFar = 1500;
  loader.load('resources/models/mountain_landscape/scene.gltf', (gltf) => {
    gltf.scene.traverse((child) => {
      if ( child.isMesh ) {
        child.castShadow = true;
        child.receiveShadow = true;
      }
    });
    scene.add(gltf.scene);
  });

  window.s = scene;

  if (useFog) {
    const vertexShader = `
    varying vec3 vWorldPosition;
    void main() {
      vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
      vWorldPosition = worldPosition.xyz;
      gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
    }
    `;

    const fragmentShader = `
    uniform vec3 topColor;
    uniform vec3 bottomColor;
    uniform float offset;
    uniform float exponent;
    varying vec3 vWorldPosition;
    void main() {
      float h = normalize( vWorldPosition + offset ).y;
      gl_FragColor = vec4( mix( bottomColor, topColor, max( pow( max( h , 0.0), exponent ), 0.0 ) ), 1.0 );
    }
    `;

    const uniforms = {
      topColor:    { value: new THREE.Color(0x88AABB) },
      bottomColor: { value: new THREE.Color(0xEFCB7F) },
      offset:      { value: 730 },
      exponent:    { value: 0.3 },
    };
    uniforms.topColor.value.copy(hemiLight.color);
    scene.fog = new THREE.Fog(scene.background, fogNear, fogFar);
    scene.fog.color.copy(uniforms.bottomColor.value);
    const skyGeo = new THREE.SphereGeometry(4000, 32, 15);
    const skyMat = new THREE.ShaderMaterial( { vertexShader: vertexShader, fragmentShader: fragmentShader, uniforms: uniforms, side: THREE.BackSide } );
    const sky = new THREE.Mesh( skyGeo, skyMat );
    scene.add(sky);
  }

  function resizeRendererToDisplaySize(renderer) {
    const canvas = renderer.domElement;
    const width = canvas.clientWidth;
    const height = canvas.clientHeight;
    if (width === canvas.width && height === canvas.height) {
      return false;
    }

    renderer.setSize(width, height, false);
    return true;
  }

  function render(time) {
    time *= 0.001;
    time += 80;

    if (resizeRendererToDisplaySize(renderer)) {
      camera.aspect = canvas.clientWidth / canvas.clientHeight;
      camera.updateProjectionMatrix();
    }

    if (!useOrbitCamera) {
      const angle = Math.sin(time * camSpeed) + Math.PI * .75;
      camera.position.set(Math.cos(angle) * camRadius, camHeight, Math.sin(angle) * camRadius);
      camera.lookAt(...camTarget);
    }

    renderer.render(scene, camera);

    requestAnimationFrame(render);
  }

  requestAnimationFrame(render);
}

main();
</script>
</html>

